Preview Panel does not work in Khmer

Thanks for reply. I did all that but is still not working.  I can see the source and target characters very well. Everything is fine in translation mode but not in the Preview mode or when it is Save Target As or Export for External Review, all are just boxes. I even mapped fonts, substitutes fonts in Windows 7 to make sure it uses correct font for Khmer Unicode fonts. The SDL claimed that it supports Khmer language but I am not sure if it ever tested.  I do not think there is a lot of people are using SDL Trados.